The purpose of this study is to examine the three-year outcome of relaxation training used as a adjunctive procedure in the treatment of essential hypertension. 260 participants will be randomly allocated to receive relaxation training or no training. All participants will be followed every two months to monitor blood pressure, and prescription of antihypertensive agents will be monitored at six-month intervals. Several other issues concerning the procedure and effectiveness of relaxation training will be examined in randomized experiments with subsamples of the participants. These include an examination of the generalization of blood pressure lowering during the working day; a study of adherence to the relaxation procedure; a test of methods to enhance the effects of relaxation training for nonresponders to initial training; and a study of the need for continued relaxation practice.